Conventionally known optical systems for vehicle headlights include an optical system using an incoherent light source such as a halogen light source, an HID light source, and an LED light source. An optical system used as a vehicle headlight is required to form a high beam light distribution pattern and a low beam light distribution pattern. The conventional optical system for a vehicle headlight forms a light distribution pattern, for example, with a reflection surface of a reflector disposed around a light source, causes light from the light source to be reflected by the reflection surface, inverts and projects the light forward through the projection lens (see Japanese Patent Application Laid-Open No. 2008-152980, for example).
Formation of a desired light distribution pattern with a hologram optical element is also known. To be specific, the hologram optical element can be disposed in front of a projection lens, and a region irradiated with a headlight is magnified by making refraction, thereby forming the desired light distribution pattern (see Japanese Patent Application Laid-Open No. Hei. 5-139203 (1993), for example).